Pump for refrigerating means



Oct. 13, 1936 M. w. KENNEY El AL 3 PUMP FOR REFRIGERATING MEANS Original Filed Jan. 6, 1933 4 Sheets-Sheet 1 Oct. 13, 1936. M. w. KENNEY EITAL I 2,057,331

' PUMP FOR REFRIGERATING MEANS Original Filed Jan. 6, 1933 4 Sheets-Sheet 2 Oct. 13, 1936. M. w. KENNEY ET AL PUMP FQR REFRIGERATING MEANS Original Filed. Jan. 6, 1953' 4 Sheets-Sheet 3 1936. M. w. KENNEY-ET AL ,381

rim? 7 FOR REFRIGERATING MEANS Qriginal Filed Jan. 6. 1933 4 Sheets-Sheet 4 Patented Get. 13, 1936 PATENT. OFFICE PUMP FOR REFRIGERATING MEANS Mahlon W. Kenney, Berwyn, and James D. Jordan, Elmhurst, Ill., assignors to General Household Utilities Company, Chicago, 111., a corporation of Delaware Original application January 6, 1933, Serial No. 650,450. Divided and this applicationJuly 16,

1934, Serial No. 735,388

- '1 Claims.

The present invention relates to refrigeration, and more particularly to a novel pump device therefor. i

In usual refrigeration, there is essentially an evaporation of a fluid refrigerant for the absorption of heat. The refrigerant is usually a volatile liquid contained in an evapoator, and evaporation or ebullition is effected by mechanical exhaustion or chemical absorption. The former is known as the pressure type of refrigeration and the latter as the absorption type. The present invention relates to the pressure type.

In such a type, is included means for converting the vapors into liquid state for re-use in the evaporator. The converting means comprises a pump frequently referred to as a compressor, and a cooling means often termed a condenser.

'I'he refrigerant generally used is sulphur dioxide but this substance has several disadvantages. It is corrosive, poisonous, and has an obnoxious odor. water, this substance forms an acid which attacks and corrodes the parts of the refrigerating device, causing leakage of the refrigerant and escape of its fumes. It is only slightly miscible with oil, so that the oil used in the system for a lubricating purposes, forms a stratum on the surface of the liquid refrigerant in the evaporator, thus reducing the evaporative effect thereof.

frigerating devices from this cause have occurred.

To remove the air, it is necessary to calla service man to service the device. The same is true when water is present in the system. The purging and recharging ofsuch a system requires considerable skill, time and effort, and is dangeroils. Ammonia as a refrigerant, from a mechanical stand point, is less desirable than sulphur dioxide. Ethyl chloride has been used but it' is poisonous among other disadvantages, and is very undesirable.

7 The present invention comprehends the use of arefrigerant which avoids all of the disadvantages mentioned, and a noveldeviceor system especiallyadapted for using such refrigerant. The refrigerant we preferably use is dichloromethane, now obtainable in substantially pure state. It has the chemical formula 01-12012. It

In the presence of moisture or,

is non-inflammable, non-explosive, non-corrosive (with or without presence of moisturelof most metals used in refrigerating devices, non-poisonous, and readily extinguishes fire, in both its liquid and gaseous or vaporous forms. At atmospheric pressure, it has a boiling point of about 105 F. and is therefore a liquid at all normal temperatures. Its density is about 1.33. Being a liquid, it is easily handled and can be simply poured at any point desired into the refrigerating system to charge it. It does not give off objectionable fumes. Its vapor has a very slight and inofiensive odor. The vapor has a higher specific gravity (about 3.0) than air, and sinks in air.

This refrigerant of our invention, is used at low pressure. This is very advantageous because it avoids any rupture in the system, andreduces leakage to a minimum. At an absolute pressure of 3.2" Hg., its boiling point is 14 F. The pressure differential of the pump in our system, is about or less than one atmosphere, and the head pressure at the pump outlet is about atmospheric. This refrigerant has a greater thermal efficiency than any other known-practical refrigerant. Its

co-efiicient of performance is 5.14 and is only 0.6

below the theoretical maximum. It requires less horse power per ton of refrigeration produced than any other known refrigerant. The terms ton of refrigeration means the amount of refrigeration effected when melting a ton of ice.

Its factor is 0.918 as against the theoretical factor of 0.821. It is miscible with oil and hence no stratum-of oil can be formed on the refrigerant in the evaporator to strangle. or choke the evaporation of the liquid refrigerant. The refrigerant, in our invention, may contain dissolved oil to the extent of 25% and the practical operative-, ness of the system occurs. without decreasing the efficiency of the system. Even when the conof evaporation is but slightly affected. In other words, if it were possible, but not at all probable under ordinary conditions, to dissolve suflicient oil as to constitute a large portion of the content of the system, the refrigerant still has the property of evaporating to the extent of producing a substantial exchange of heat, not matarially different from the action of the refrige rant when it has practically no oil dissolved in it.

Another object of the invention is to provide a. novel pump capable of handling the vapors exhausted 'from the refrigerant referred to. Preferably a pump of the rotary-piston type is used since it will exhaust and pass a large volume tent of the evaporator is half oil, the efficiency of vapors for a given size of pump. Qne pound of CHzClz expands to about seven times the volume oi the ordinary refrigerant, such as S02. It is necessary to circulate from five to ten percent more CH2C12 per hour than is required for such refrigerant as S02, for a given refrigerating effect, the ratio in gas or vapor volume being about 7 to 1. Therefore, a rotary piston pump which operates at a speed to exhaust the vapors at a rate to efl'ect the desired heat exchange in the evaporator, is comprehended by our invention.

Another object of the invention is to provide a novel pump with vanes with ends so shaped or curved as to prevent liquid logging of the pump when the resistance acting against the vanes is such that the component forces thereof acting along the center lines of the vanes, exceed the component centrifugal forces acting outwardly along the same hnes.

A further object of the invention is to provide a novel pump of the rotary piston type with the vanes thereof so arranged in secantal relation that at the starting of the pump the vanes may so move by inertia or remain more or less inert as to eifect an unloading of the pump of any liquid present therein.

Another object of the invention is to provide a novel pump having a volumetric displacement of about five cubic inches per revolution and a displacement of approximately five cubic feet per minute of the vapor of the refrigerant, the vanes of the pump being so arranged in secantal relation as to effect these displacements.

The invention also comprehends the servicing of the system by simply effecting an opening at any desired point in the system or circuit of the system, to subject it to atmospheric pressure without loss of the refrigerant.

Another object of the invention, is to provide a novel trap and refrigerant receiver, which acts to control the passage of liquid refrigerant to the evaporator, and which has a capacity for receiving and holding the refrigerant charged in the system, until such time as the system operates to circulate the refrigerant for normal operation.

A further object of the invention is to provide a novel process or method of refrigeration with a refrigerant having the physical characteristics and properties mentioned.

Other objects, advantages, capabilities, features and process steps are comprehended by the invention as will later appear and as are inherently possessed by the invention.

Referring to the drawings,

Fig-. 1 is a diagrammatic or schematic view of a system constructed in accordance with the invention;

Fig. 2 is a longitudinal sectional view taken through the motor-pump unit of the system;

Fig. 3 is a transverse sectional view taken in a plane represented by line 3-3 of Fig. 2 of the drawings;

Fig. 4 is a fragmentary sectional view taken in a plane represented by line 4-4 in Fig. 2 of the drawings;

Fig. 5 is an end view of the rotor or rotary piston of the pump without the blades or vanes;

Fig. 6 is a sectional view taken in planes rep resented by line 66 in Fig. 3 of the drawings;

Fig. 7 is a diagrammatic and mathematical representation of the essential features of the pump, and showing the determination of the curvature of the contacting edges of the piston vanes of the pump;

Fig. 8 is a perspective view of one of the vanes or blades used in the pump;

Figs. 9 and 10 are enlarged fragmentary sectional views of the pump showing the relation of paits thereof during the operation of the This is a,division of our co-pending application Serial No. 650,450, filed January 6, 1933.

Referring more in detail to the drawings, the embodiment selected to illustrate the invention is shown in the form of a closed circuit or circuitous passage containing a given quantity of refrigerant I such as dichloromethane or similar refrigerant having substantially the same physical characteristics and properties. The circuit comprises an evaporator 2, a pressure converter or pump 3 connected to the evaporator by a duct 4, a cooler or condenser 5 connected to the pump 3 by a duct 6, and a trap and receiver i connected to the condenser 5 and the evaporator 2 by ducts 8 and 9 respectively.

In the duct 4 is preferably connected a flexible or yieldable coupling ID of the sylphon bellows type, and a check valve ll having a light weight sensitive valve disc l2. 'I'he condenser may be of any suitable type, such as of the serpentine form and provided with heat radiating fins I3, this condenser being located in a plane parallel to the plane of rotation of a fan I secured to the end of a shaft l5 of the motor pump unit.

The evaporator shown comprises a metal compartment I6 of rectangular form, and about the side and bottom walls of which, is embraced a corrugated sheet I! having corrugations it which form circulating channels or passages IQ for the refrigerant i about the walls of the chamber IS, the upper end portions 20 and 2| of the sheet I! being joined in a seam or joint 22 are shown in Fig. 1. This provides for a dome or evaporating space 23 within the evaporator and above the crown sheet 23 wherein the normal liquid level is maintained as indicated at 25. At a suitably high the side wall of the chamber I6 is formed with a cross duct or channel 26 adapted to communicate at points opposite the channels or corrugations I 8, with passages IS, an end of the cross duct 26 being connected with the duct 9. The space Within the chamber l6 constitutes what is usually termed the freezing zone and may contain shelves 2? and 28 for suitably supporting trays, such as ice cube trays and the like.

The coupling I 0 is preferably of the sylphon bellows type comprising several folds 29 and end flanges 30- and 3! suitably spun over flanges formed on the ends of the segments of the duct 4. This coupling is flexible and yieldable so as to dampen and to prevent transmission of mechanicalvibrations and sound to the duct 4 and connected parts, from the pump and the like.

The check valve II is preferably located in the duct 4 as close as possible to the inlet 32 of the pump. The position of the check valve in Fig. 1 is remote from such inlet simply for the sake of clearly showing the valve, but in the actual device the check valve is proximate to the inlet 32. This check valve contains a thin light weight disc i2 which may be of metaLbakelite, or any suitable material wherebyit is sensitively active to small changes in pressure within the range of pressures (partial vacuum) used in the 2,057,381 system. The discv l2 may seation a seat 33 as shown. 'In orderthat it may not jam or be canted off its seat, the disc l2 may be limitedinits movement by a stop 34 'adjustably located inthe upper part of the valve casing and above thedisc [2 at a suitable and given distance. a

- From the above it will be: apparent that the system comprises a main circuit or circuitous passage in which is charged a given quantity of liquid refrigerant, such as dichloromethane or other refrigerant having substantially the same physical characteristics and properties. "Within this circuit is an auxiliary circuit comprising the circulating passages l9 and the dome space 23 where the refrigerant receives an induced circu-. lationby reason of the refrigerant'from the con denser and trap, entering by way of thecrossduct 26. Also in the main circuit is included the pump 3, the condenser and thetrap 1, the latter acting to controllably permit the passage of the liquid refrigerant to the evaporator but preventing the passage of the'vaporsthereof.

The trap and' receiver 1 comprises a chamber 35 ofsuch/a size as to contain all of the liquid,

refrigerant charged in the system, under certain conditions as laterexplained. At the upper end of the chamber 35 is connected an inlet means secured by a fitting 31 to the-duct 8. To the inlet is connected a porous member 38 adapted to filter the refrigerant entering the chamber; Also at a high point of the chamber 3.5 is providedor connected a relief valve 42 suitably adjustable by turning the head 42. If air enters the system the pressure vmay build up above atmospheric pressure which is the normal head pressure on the outlet side of the pump and condenser. As for example, should air enter the system and should it produce a pressure of a few pounds per square inch, the valve 42 may open to release the air, after which the valve closes. In this way the system is purged of truant air or like gas. I

At the base of the chamber is provided a sump to which is secured a valve stemguide and trap throat member 44 having guide ribsbetween which isfreely slidable avalve stem 46 rigidly securedat its-upper end to a-buoyant member 41 which is preferably in the form of a hollow ball of magnetic material, such assteel or iron or even'nickel. The purpose of this is that in the event of the valve of the trap sticking an electromagnet may be passed about the chamber 35, and

when energized, will effect a stress on the member 41 so as to move it and the valve connected to it,

to release it from its seat. Above the member 41 is located a cross member 46 having its ends suitably secured to the sidewalls of the chamber 35. This member acts as a limit stop for the upward movement of the member 41. I l

To the lower end of the member 44 is secured a;fitting 49 suitably connected by a fitting 50 to the duct 9 leading to theevaporator' 2. The fitting has a valveseat "against'whi'ch a cone face maybeprovided for theradiation of heat.

The trap is sofldesigned th'at it will act, i. e. open and closerapidly or 'witha snap action. Normally, with the valve closed, the liquid refrigerant accumulates in the sump to a level about midway, the member 41.v At that point, the member 41 is buoyantly-afiected, and it suddenly rises, thus simultaneously lifting the valve 52 from its seat. The liquid refrigerant immediately passes through the valve port and the duct 9"to the evaporator. As the liquid level in the sump descends to about a quarter or a fifth of the height of the member, the latter suddenly descends and closes the valve, thus preventing further passage of the refrigerant, and particularly preventing the escape of vapors or gasses to the duct 9.

- The force acting to hold the valve closed is the vacuum effective through the evaporator 2 and duct 9, plus the weight of the buoyant mem- "ber 41 and the valve stem 46. As the liquid refriger'ant from the 'condenseraccumulates'in the sump 43, a buoyant force on the member 41 and stem '46 accordingly increasesj'to'the'point where it equals'the force'acting to hold the valve closed;

Up to this point the valve remains closed. When the buoyant forceexceeds the effectof the vacuum plus the Weight ofth'e members 41 and 46,

the buoyant mei'riber suddenly rises and the valve is quickly opened."*At the'instaht or opening, the suction" force acting on; the valve, is-removed; so

'that the buoyant force acts immediately'to raise" the float and the valvecompletely'ofi its seat. The buoyant force required to break the seal between the valve and its seat, is greater than the force now acting downwardly on the members 41 and 46, this force being only the weight of the members 41 and 46. A limit stop 48 is located to limit the upward movement of the members '41 and 46. The movement is a small movement in order that the trap may be sensitive and act quickly both when opening and closing. The

buoyant force of the liquid present in the trap at the time of opening-of the valve, is more than that necessary to just hold the member 41 in contact with the limit stop 48'. When the valve opens,

the liquid flows to the evaporator by way of the duct. 9, and the buoyant force accordingly decreases;

members 41 and 46, the valve rapidly closes. At the instant when the members Hand 46 start to move. downwardly,-the buoyantforce is decreasing and the suction in duct.9 is efie ctive through the member 44, to rapidly increasethej'force tending to lower the members 41 and 46'andto close When the buoyant force decreases to I I the point where itis equal to the weight of the 5 the valve. This effects a snap actionof the valve.

Since-the -movement of the "valve is small,- its action is sensitive. After the valve is closed, the

vacuum acts to hold it closed until thebuoyant force-of theaccumulating liquid again reaches a point equalto the weight of the members 41 and 46 and the vacuum acting on the valve. i

The device is a trap and is designed to main- .tain a liquid seal inthe liquid chamber, that is, to maintain'a separationof gas and liquid, so that no gas can escape to the evaporator. It prevents the circulation of the gas which would, if not prevented, greatly reduce the refrigerating eifect.

Thechamber 35 is designed to have a capacity for holding or containing all of the refrigerant charged in the system should at any time the system stop circulating. As for example, should moisture enter the system and should it freeze in the duct 9, the system will continue tooperate to evaporate all of the refrigerant in the'evaporator 2, and condense'the vapors to liquid, the liquid entering thechamber 35. The opening" of the trap valve 52 would not permit flow tothe evaporator because of the ice plug in the duct 9. After all of the refrigerant has thus been evaporated and condensed andfed into the chamber 35, the temperature of the evaporator and connected parts, such as the duct 9, will rise, and the ice plug will melt. Immediately, the liquid will flow from the chamber 35, the valve 52 being open, and the evaporator filled. The operation of the device continues normal. So far as the user of the system is concerned, the device has operated in the normal way except a defrosting of the freezing compartment may be noticed. The motor'is not stopped because of the blocking of the liquid, and the operation of the system is not interfered with. No high head pressure is developed and there is no stalling of the system. Dehydration, draining and refilling of the system is unnecessary.

The means for converting the vapor to liquid, comprises a pump 3 of the rotary piston type and the condenser 5. This pump is especially designed to handle a large volume of vapors given off from the particular refrigerant used. It is shown more. in detail in Figs. 2 to 10 inclusive of the drawings.

The pump comprises a cylinder or stator 55 and end plates or heads 56 and 51. The stator is normally secured to the head 51 by a pair of cap screws 58 (Figs. 3 and 6) passing through suitable longitudinal bores formed in the wall of the cylinder 55, and threadedly engaged in the head 51 (Fig. 5). Likewise, cylinder 55 is secured to the head 51, and the head 56 is secured to the cylinder 55 by means of bolts 59 passing through suitable bores formed in the head 56 and the wall of the cylinder 55, and threadedly engaged in the plate or head 51 (Figs. 2 and 3).

In the wall of the stator 55 is provided an inlet chamber 68 communicating with a passage 6| also formed in the stator wall and leading to a passage 62 formed in the head 51. (Figs. 3 and 6.) The outer end of passage 62 is headed to receive a fitting 62' secured thereto by suitable means as bolts 63, a gasket 64 sealing the connection (Figs. 3 and 6). The stator 55 is also provided with outlet ports 65 leading into a passage 66 formed in the wall of thestator, the passage 66 leading to a passage 61 formed in the head 56 and being connected to a fitting 68 and a delivery duct 69. (Figs. 2 and 3.)

- Within the stator 55 is eccentri'cally and rotatably located a piston or rotor 18 having integral shaft portions 1| and 12 rotatably supported in bearing bushings 13 and 14 secured in hearing hubs 15 and 16 respectively formed in the heads'56 and 51. (Figs. 3 and 6.) The piston 18 is provided with a number of longitudinal passages 11 opening at their ends into annular channels 18 and 1.8 formed in the ends of the piston 18. The shaft portions 1| and 12 where they C011? nect with the piston 18, are reduced in diameter to provide annular channels 88 and 8| opposite channels 18 and 19 in the ends of the piston. The channel 88 communicates with the exterior by way of a passage 82 provided in the head 56 and leading into a recess 83 formed in the head 56.

Longitudinally of the piston 18 and secantally from the passages 11 are provided slots or races in which are disposed blades or vanes 84 the outer edges 85 of which are curved on a shorter radius than the radius of the rotor 18, and are adapted to contact the inner surface 86 ofthe stator along different lines of contact from toe 81 to heel 88 and from heel 88 to toe 81 of the curved face 85 during a rotative cycle of the piston or rotor 18.

(Figs. 3, 8, 9, and 10.) This distributes the frictional contact between the vanes 84 and the inner surface. 86 of the stator thereby reducing to a minimum the wear on the vanes 84. The line of contact 89 between the piston 18 and the inner wall of the stator 55 is the line of seal between the two relatively rotative parts (piston and stator) of the pump, and this line of seal is proximate to the outlet ports 65 of the stator 55.

The vanes are disposed not radially of the rotor or stator, but at an angle so that the angle between the planes of the vanes and the tangent plane at the line of contact of the rotor with the stator wall, is substantially the angle of static friction or in other words the angle of slip. Since the coefficient of friction decreases with the velocity of the relatively moving surfaces, the friction between the vane edges and the stator surface is reduced proportionately to the rotative velocity of the piston, and since the piston rotates at several hundred revolutions per minute, it will be seen that the kinetic friction of the contacting parts is small and they wear very little. Even this small friction is reduced further by the use of oil.

The disposition of the vanes is in planes secantal to the rotor 18 or tangential to a circle concentric to the axis of the rotor 18 and whose radius is equal to or greater than the difference of the radii of the stator and rotor. Such a circle is represented at 98 in Fig. '7.

The limiting angle of friction is determined by the coefficient of friction between the vane edge and the pump body. If the coemcient of friction varies, the angle varies as the tangent of the angle. With the coefficient of friction peculiar to the use of steel on steel, the best limiting angle is about 17. The angle is that between the center line of the blade or vane and the radius of the pump body through the point of contact between the blade and the pump body where the angle is at a minimum. In this case the minimum angle is when the toe 81 touches, and the maximum angle is when the heel 88 touches. See Figs. 7, 8, and 10.

The frictional resistance is along the tangent to the inner periphery 86 of the pump stator at the point of contact. The force for moving the blade, is along the center line of the blade, and results from a component of the centrifugal force of the pump rotor, and the pressure of the oil and gas at the back edge of the blade. The total force tending to move the vane outward may be resolved into two components, one acting along the tangent to the stator at the point of contact, and the other along a normal to the tangent at the point of contact. The component force acting along the tangent is equal to or greater than the frictional force acting in the opposite direction along the tangent, and is that force which tends to tilt the blade forward. The critical angle of friction is that between the center line of the blade and the normal to the tangent of the pump rotor at the point of contact. For contact of steel on steel, the minimum or critical angle is about 17 at the toe of the blade. When the contact is at the heel, this angle is about 30, that is, it is a greater angle. When rubbing steel on cast iron, the factors are about the same. When using bronze, brass, die cast metal, aluminum, and the like against steel, cast iron, bronze and the like, the critical or minimum angle is smaller.

The radius of curvature of the blade bears a definite relation to the radii of the pump stator and rotor, and maybe determined geometrically as follows:

Referring to Fig. 7, let p (rho) =the radius of curvature of the blade edge 85,

d=the thickness of the blade,

R=the radius of the stator,

r=the radius of the rotor,

A=the center or axis of the rotor,

=the center or axis of the stator,

IB=the intersection of the center-line of the toe contacting blade and the line passing through the centers A and O,

C=the intersection of the center-line of the heel contacting blade and the line passing through the centers A and O,

D=the intersection of the front face of the toe contacting blade and the line of the centers A and 0.

E=the intersection of the back face of the heel contacting blade and the line of the centers A and 0 when this blade is in the full lines at 84 and in dotted lines at 8t when rotated 180 to'bring it into parallelism with the toe contacting blade shown in full lines at 84. The rotation of 180 of the blade 84 to position 84 is to assist in the solution of the geometric equations.

First the distance DE is determined as follows:

i and substituting In similar geometric figures, the homologous parts are proportionate to each other. When the blade contacts atits toe, the angle between this blade and the radius of the stator, is at its minimum. Similarly, when the blade contacts at its heel, the angle between this blade and the radius of the stator, is at its maximum. The difference between the maximum and minimum angles, is the angle of oscillation of the blade edge, and this angle is equal to the angle measured by the arc of the blade edge from toe to heel. Then the radius of that are is to the radius of the stator as the arc of the blade edge is to the arc .of the angle of oscillation. The horizontal projections of these arcs on the line of the centers A and 0 of the rotor and stator, are measured by d and DE on the line EE' of the diagram of Fig. 7.

Therefore 1 DE R where p is the radius of curvature of the blade edge. Thus 5i l DE 2R2r+d For example, if

#1000" then This is approximately The rocking or oscillating of the blade face is not for the full extent or width of the face, but is such as to leave slight angles for oil to lubricate, and to prevent the toe and the heel from scoring the inner surface of the stator, and also to prevent the toe from scraping away the oil.

Referring to Figs. 9 and 10 it is apparent that when the blade 8 is contacting at its heel there is a small dihedral angle 9! back of the heel (Fig. 9) where oil may enter for lubrication and where there may be suflicient clearance to prevent the corner from scraping against or scoring the surface 86 of the stator. Likewise, as shown in Fig. 10, when the blade is contacting at its toe, there is a small dihedral angle 92 in front of the toe where oil may enter for lubrication and where there is sufllcient clearance to prevent the corner from scraping away the oil or from scraping against or scoring the surface 86 of the stator.

In the event of increased pressure on the front side of the blade, such as if and when liquidshould enter the pump, the pressure may act into the angle 92 so as to force the blade inward, and thus prevent a logging of the pump. That is, when the resistance acting against the blade is such that the component force thereof acting along the center-line. of the blade exceeds the component centrifugal force acting to move the blade outwardly, the blade will move inwardly and thus relieve the pump, similarly to preventing the logging mentioned above.-

The particular angular disposition of the blades is also of advantage for unloading the pump,

that is, when the rotor starts, the blades will move inwardly by reason of inertia and thus relieve the differential pressure. If the blades were radially disposed, this unloading could not occur and the blades would cock or jam with -very much like a toggle action, and prevent the proper starting of the pump. With the blades at proper angles, after the unloading occurs, and the rotor rotates at proper speed, theblades then move outwardly by centrifugal force and eifect proper Sealing between the edges of the blades and the surface 86 of the stator.

The passages 11 at the rear or inner edges of the blades, and the communicating channels 18 and 19, act as a compensator for the displacement of the oil by the different movements of the blades. As for example, as one blade is moving outward (see lower blade in Fig. 3) and another blade is moving inward (see upper blade in Fig. 3) the oil surges or is displaced by the latter and flows into the passage ll of the former.

' head 56.

The pumpis submerged in oil 93 contained in a housing 94 which is sealed and secured at its open end 95 against the face 98 of the plate or head 51 by means of bolts 91 passing through suitable apertures provided in member 51, and threadedly engaged in the end portion 95 of the housing (Figs. 2 and 6).

The upper part of the housing is provided with a dome 98 with which are formed bailie walls 99 and I00 dividing the dome space into chambers IOI, I02 and I03 (Figs. 3 and 4). The wall 99 has a port I04 at an end thereof for establishing communication between chambers WI and I02, and the wall I00 has a port I05 at the other end thereof for establishing communication between the chambers I02 and I03. (Figs. 3 and 4.) The chamber I03 has an outlet passage I06 leading to a fitting I01 secured in place by bolts I08, a gasket I 09 sealing the fitting to the dome (Figs. 3 and 4). In this way the chambers IOI, I02 and I03 with the ports I04 and I05, and the outlet I06, provide a tortuous passage for the compressed vapors discharged from the pump by way of the discharge duct 69 which extends upward at a high point in chamber IOI. '(Figs. 2, 3, and 4.) Moreover, this bailiing causes the oil carried over by the compressed vapors, to be removed, the oil returning by gravity to the oil 93 in the housing 94. It will be noted that the lower edges of the walls 99 and I00 dip below the level of the oil 93 in the housing 94.

The shaft part 12 has an integral extension IIO provided with a tapered part III and a reduced part II2. To the tapered part I II is secured a core member II3 suitably held in place by a retainer II4 thrust against the end of the member II3, the retainer being secured to the shaft part II2 by means of a screw or bolt H5. The fan I4 (Fig. 1) is carried by the retainer I I4. The retainer is also keyed to the member I I3 by dowels II6 extending into sockets provided in the end of the member H3 and into recesses II1 provided in the sides of the retainer II4.

0n the member H3 is carried a laminated motor rotor or core II8 clamped between rings H9 and I fastened together in any suitable manner as by bolts I2I passing therethrough and through the-laminations of the rotor I I8. Concentric with the rotor II 8 is located a laminated stator I22 clamped against ring I23 and fastened together by bolts I25 passing therethrough and through the laminations of the stator I22. A suitable winding I26 is carried by the stator.

The stator I22 is held in place by way of the ring I23 which is secured in any suitable manner to a ring I21 forming a part of a frame rigidly connected between the pump 3 and the motor. This frame is of frusto conical form and comprises the ring I21 and arms I28 formed integral with an annular part or flange I29 of the head or plate 51. (Figs. 1, 2, 4, and 6.)

It will be noted that the motor is on the overhanging or extended part of the shaft and has no direct bearing of its own. The shaft has, but two bearings which are in the pump casing, namely the pump bearings 13-15 and 14-18 in the heads or end plates 58 and 51 of the pump? The motor is of the capacitor type and has no slip rings or sliding contacts of any kind.

For the purpose of preventing escape or leakage of oil from and entry of air and dust into the pump bearings and the pump, the shaft, adjacent the pump bearing 14-16, is provided with a double seal of the sylphon bellows type. The bearing 13-15 is submerged in the oil 93 and does not require this seal. The seal comprises bearing rings I 30 and I3I respectively in thrust bearing contact with shoulders I32 and I33 of the shaft portion 12 and core member II3. (Fig. 2). These rings I30 and I3I may be made of suitable anti-friction metal or alloy, such as bronze and the like. Against the rings I 30 and I3I are pressed thrust rings I34 and I35 under the action of helical springs I38 and I31 reacting against the inner flanged portions of shells I38 and. I39, the outer flanged portions of which are clamped between a hub portion I40 of the head 51 and a ring MI and between a ring I and a ring I42, the clamping action being effected by clamping bolts I43 passing through the outer flanged portions of shells I38 and I39 and rings I M and I42 and threadedly engaged in the hub portion I40. Between the inner flanged portions of shells I38 and I39 and the rings I34 and I35 are secured in sealing relation, sylphon bellows I44 and I45 which are adapted to flex both axially and transversely or radially, and also act as seal walls between the shells I38 and I39, and the rings I34 and I35. The hub portion I40 is provided with a channel I46 for oil, the oil being supplied from the charge in the housing 94 by way of a passage I41 provided in the head 51 and communicating with the interior of the housing 94 above the pump stator 55. (Fig. 2). In the space between the shells I38 and I39 and in the space between them and the shaft part H0, is provided a space filled with 011 I49. This oil is supplied by way of a duct I 49 communicating with a passage I50 provided in the hub portion I40 of the head 51, and a passage I 5I provided in the ring I (Fig. 2). The space around the seal parts I45, I35 and I39 is open to the air. It will be seen that the inner seal, comprising parts I30, I34, I44 and I38, is oil sealed on both the inside and outside so that any escape of oil by the bearing members I 30 and I32, will return to the oil space I48. 0n the other hand any air that may enter through the outer bearing member I33 and I3I, will pass as bubbles in the space between the seals and pass out through the vent I52 provided in a cap I53 on the duct I49. The unit may be suitably supported by legs I54 and I55 secured by bolts I56 and I51 to the housing 94 and frame part I21. (Fig. 2).

In operation, the motor drives the pump and fan, the latter being located to force cooling air through the condenser 5. The charge of dichloromethane may be poured into the chamber 35 by way of the connection 35 after disconnecting the fitting 31. This chamber acts as a measuring means for determining the amount of refrigerant to be charged. After reconnecting the fitting 31, and with the motor running, the pump creates a vacuum in the evaporator 2 thus causing the refrigerant to flow from the chamber 35 by way of the duct 9 to the evaporator, the valve 52 being vapors escape at the valve II, it may then be closed.

The continued operation causes the refrigerant in the evaporator to boil or evaporate whereby heat is absorbed through the walls of the evaporator, thus cooling the air in the chamber l6 and surrounding the evaporator.

In order that the refrigerant in the evaporator may circulate, the duct 9 leads-into a cross duct 26 which communicates with the passages i8 at a low point. The incoming refrigerant causes an upward flow of the refrigerant in the passages i8 so as to induce a circulation of the liquid in the evaporator.

The vapors pass from the evaporator to the duct 1 and through the flexible coupling I0 and the check valve 1 I to the pump. This check valve ii is located as close as possible to the inlet iii of the pump. (Fig. '6). The pressure in the evaporator above the liquid, is about 3.2" Hg. ab-

, solute and the temperature about ld F. l The pump acts to compress the vapors to about atmospheric pressure which is the pressure (termed the head pressure) at the outlet of the pump. The temperature of the compressed vapor discharged from the pump is a few degrees above the temperature of the surrounding atmosphere.

The rotor of the pump contacts the stator at the seal line. As the piston rotates, the blades are moved outwardly by centrifugal force, so that the curved edges 85 slide along the surface 86 of the pump stator. At the seal line the blade contacts intermediate the toe and heel. See the upper blade in Fig. 3. As the piston rotates in anti-clockwise direction as viewed in Fig. 3, the blade moves outwardly and against vapors passing from the inlet chamber 60, and the contact moves towards the heel. See the blade at the left of Fig. 3. Then as the blade passes the end of the port of chamber 6|], a quantity of vapor is trapped between that blade and the blade leading it. See the lower and right hand blades in Fig.3. These blades are now moving inward and the space between these blades is gradually decreasing, whereby the trapped vapors are compressedy See the space between the right hand blade and the upper blade in Fig. 3. Then the compressed vapor is discharged through the Outlet ports Q5.

The lower blade is now contacting intermediate the heel and toe, while the right blade shown in Fig. 3 has contacted at the toe and the point of contact is now moving toward the heel.

"Hence, it will be seen that during a revolution each blade varies its contact with the inner surface 860i the stator, from heel to toe and from toe to heel. It will also be noted that as a blade is moving inwardly, the opposite blade is moving outwardly, so that the former displaces oil in a passage H so as to cause it to flow to the channels I8 and 19 (Fig. 2) and thence into another passage IT. This displacement may not be even in oppositely disposed passages Ti and hence a; relief passage 82 is provided for the excess oil to pass into the body of oil 93 or for replacing oil to pass into the pump.

When starting, the blades will move inward by reason of inertia, the'displaced oil in passages i1 passing to channel 18 and relief passage 82. As the piston speeds up, the centrifugal force moves the blades outward for proper sliding contact with the stator. Excessive resistance due to presence of a liquid in the pump or pressure of the fluid in the pump, will act on the blades to resolve a component force along the blade to overcome the component centrifugal force acting along the blades in the opposite direction, so as to cause the blades to recede, and relieve the pump of the excessive resistance. This may be aided by the fluid enteringunder the toe of each blade to force the blade inward.

The compressed vapors are conducted by way small in diameter as possible to prevent any boil-- ing of the liquid therein under the effect of the vacuum acting in the evaporator and in the duct 9.

Some oil is carried over but it dissolves in the liquid refrigerant. This oil may be separated from the refrigerant in the evaporator by capillary attraction of the solution and an evaporation of the refrigerant component leaving the oil component for draining away or for returning to the pump housing.

The pump, the motor and the fan are on a single shaft, the pump bearings being the sole bearings for the shaft. Since the pump is submerged in oil, these hearings are automatically lubricated. There is no other bearing.

Should any leakage occur, as entry of air in the evaporator or in the line from the evaporator to the pump, the head pressure may increase above atmospheric, a few pounds per square inch. This air may be vented through the valve dl (Fig. 1-1). A motor circuit trip may be set at a pressure, say 15 to 20# so that should the head pressure become that high. the motor will be stopped, and the leak may be repaired. Then with the vent valve M open, and the device started, the air is purged from the system, as above explained. The device then operates normally.

While we have herein described and upon the drawings shown an illustrative embodiment of the invention, it is to be understood that the invention is not limited thereto 'but comprehends other constructions, 'details, features, arrangement of parts and process steps without departing from the spirit of the invention.

Having thus disclosed the invention. we claim:

1. In a rotary piston type of pump having a rotor and a stator, a piston blade secantally and reciprocably mounted in said rotor and having a curved contacting edge for moving over the surface of the stator the radius of curvature of said edge being less than the distance of the center line plane of the blade from the axis of the rotor and the center of curvature of said curved contacting edge being between the center line plane of the blade and a radial plane of said rotor parallel to said plane of the blade.

2. In a rotary piston type of pump having a rotor and a stator, a piston blade secantally dis-. posed in the rotor and having a curved contacting edge for moving over the surface of the stator the radius of curvature of said edge being equal t 2R-2t+d where R and r are the radii of the stator and rotor respectively and d is the thickness of the blade.

3. A vane for a rotary piston pump for a refrigerating system including a liquid refrigerant comprising a body portion reciprocably movable and secantally mounted in the piston of the pump and having a curved edge portion within the bounds of the surfaces of the vaneand formed on a circular are having a single center of curvature, said edge portion slidably contacting the cylinder of the pump, the curved surface of said edge portion having its center of curvature in a plane parallel to and between the plane of reciprocating movement of said vane and the radius of the piston parallel to said plane of reciprocation of said vane, the radius of curvature of said curved surface of the vane being less than the normal distance between the plane of reciprocation of the vane and a radial plane of the piston parallel to said plane of reciprocation of said vane.

4. A pump for a refrigerating system including a liquid refrigerant, comprising a cylinder, a piston rotatable in and eccentrically related to said cylinder, and reciprocably movable and secantally mounted vanes. carried by said piston and having curved edges on a circular arc of a single center and having sliding contact with said cylinder, the radius of curvature of said edges being a function of the radii of said piston and cylinder and being less than the radius of either said cylinder or piston and being less than the normal distance between the plane of reciprocation of the vane and a radial plane of the piston parallel to said plane of reciprocation of said vane.

5. A pump for a refrigerating system including a liquid refrigerant, comprising a cylinder, a piston rotatable in and eccentrically related to said cylinder, and movable vanes reciprocably and secantally mounted in said piston, the contacting edges of said vanes being so curved and arranged as to each have a travelling contact with the cylinder approximately from toe to heel and from heel to toe of said edge during the rotative cycle of the piston and blades, said edges being so curved beyond the limits of the range of said contact travel that the blades move inwardly to prevent liquid logging when the resistance acting against the vanes is such that the component forces thereof acting along the center lines of the vanes exceed the component centrifugal forces acting to move the vanes outwardly, said vanes being disposedin planes beyond the axes of said piston and cylinder, the radius of curvature of said curved surface of the vane being less than the normal distance between the plane of reciprocation of the vane and a radial plane of thepiston parallel to said plane of reciprocation of said vane.

6. In a refrigerating system comprising a. circuit containing a quantity of liquid refrigerant and including as part thereof means for causing an evaporation of the liquid refrigerant for absorption of heat and for converting the vapors thereof to liquid state, said means comprising a rotary piston pump having a rotary piston eccentrically mounted in the cylinder of the pump, vanes reciprocably movable and secantally mounted in said piston and cooperating with the cylinder for increasing the pressure of the vapors drawn into the pump, said vanes having curved edges contacting with the cylinder, the curvature of said edges having a radius of curvature less than the normal {distance between the plane of reciprocation of the vane and a radial plane of the piston parallel to said plane of reciprocation of said vane, whereby the lines of contact between said edges and the pump cylinder oscillate across the curved face of said edges during each rotative cycle of said piston, said vanes being disposed in planes beyond the axes of said piston and cylinder.

'7. In a rotary piston type of pump having a rotor and a stator, said rotor being eccentrically mounted within said stator, a piston blade reciprocably and secantally mounted in said rotor and having a curved contacting edge within the bounds of the surfaces of said blade for moving over the surface of the stator, the curvature of said edge being so constructed and arranged with relation to the center of rotation of the rotor and the curvature of the stator as to have a travelling contact with the surface of the stator from toe to heel and from heel to toe of said curved contacting edge, the center of curvature of said curved contacting edge being between the plane of the blade and a radial plane of the rotor parallel to said blade plane and the radius'of curvature of said curved contacting edge being less than the normal distance between the plane of reciprocation of the blade and a radial plane of the rotor parallel to said plane of reciprocation of said blade.

MAHLON w. KENNEYQ JAMES D. JORDAN. 

